test: add firmware_class loader test

This provides a simple interface to trigger the firmware_class loader
to test built-in, filesystem, and user helper modes. Additionally adds
tests via the new interface to the selftests tree.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/testing/selftests/Makefile

@@ -11,6 +11,7 @@ TARGETS += vm
 TARGETS += powerpc
 TARGETS += user
 TARGETS += sysctl
+TARGETS += firmware
 
 all:
 	for TARGET in $(TARGETS); do \

tools/testing/selftests/firmware/Makefile

@@ -0,0 +1,27 @@
+# Makefile for firmware loading selftests
+
+# No binaries, but make sure arg-less "make" doesn't trigger "run_tests"
+all:
+
+fw_filesystem:
+	@if /bin/sh ./fw_filesystem.sh ; then \
+                echo "fw_filesystem: ok"; \
+        else \
+                echo "fw_filesystem: [FAIL]"; \
+                exit 1; \
+        fi
+
+fw_userhelper:
+	@if /bin/sh ./fw_userhelper.sh ; then \
+                echo "fw_userhelper: ok"; \
+        else \
+                echo "fw_userhelper: [FAIL]"; \
+                exit 1; \
+        fi
+
+run_tests: all fw_filesystem fw_userhelper
+
+# Nothing to clean up.
+clean:
+
+.PHONY: all clean run_tests fw_filesystem fw_userhelper

tools/testing/selftests/firmware/fw_filesystem.sh

@@ -0,0 +1,62 @@
+#!/bin/sh
+# This validates that the kernel will load firmware out of its list of
+# firmware locations on disk. Since the user helper does similar work,
+# we reset the custom load directory to a location the user helper doesn't
+# know so we can be sure we're not accidentally testing the user helper.
+set -e
+
+modprobe test_firmware
+
+DIR=/sys/devices/virtual/misc/test_firmware
+
+OLD_TIMEOUT=$(cat /sys/class/firmware/timeout)
+OLD_FWPATH=$(cat /sys/module/firmware_class/parameters/path)
+
+FWPATH=$(mktemp -d)
+FW="$FWPATH/test-firmware.bin"
+
+test_finish()
+{
+	echo "$OLD_TIMEOUT" >/sys/class/firmware/timeout
+	echo -n "$OLD_PATH" >/sys/module/firmware_class/parameters/path
+	rm -f "$FW"
+	rmdir "$FWPATH"
+}
+
+trap "test_finish" EXIT
+
+# Turn down the timeout so failures don't take so long.
+echo 1 >/sys/class/firmware/timeout
+# Set the kernel search path.
+echo -n "$FWPATH" >/sys/module/firmware_class/parameters/path
+
+# This is an unlikely real-world firmware content. :)
+echo "ABCD0123" >"$FW"
+
+NAME=$(basename "$FW")
+
+# Request a firmware that doesn't exist, it should fail.
+echo -n "nope-$NAME" >"$DIR"/trigger_request
+if diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not expected to match" >&2
+	exit 1
+else
+	echo "$0: timeout works"
+fi
+
+# This should succeed via kernel load or will fail after 1 second after
+# being handed over to the user helper, which won't find the fw either.
+if ! echo -n "$NAME" >"$DIR"/trigger_request ; then
+	echo "$0: could not trigger request" >&2
+	exit 1
+fi
+
+# Verify the contents are what we expect.
+if ! diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not loaded" >&2
+	exit 1
+else
+	echo "$0: filesystem loading works"
+fi
+
+exit 0

tools/testing/selftests/firmware/fw_userhelper.sh

@@ -0,0 +1,89 @@
+#!/bin/sh
+# This validates that the kernel will fall back to using the user helper
+# to load firmware it can't find on disk itself. We must request a firmware
+# that the kernel won't find, and any installed helper (e.g. udev) also
+# won't find so that we can do the load ourself manually.
+set -e
+
+modprobe test_firmware
+
+DIR=/sys/devices/virtual/misc/test_firmware
+
+OLD_TIMEOUT=$(cat /sys/class/firmware/timeout)
+
+FWPATH=$(mktemp -d)
+FW="$FWPATH/test-firmware.bin"
+
+test_finish()
+{
+	echo "$OLD_TIMEOUT" >/sys/class/firmware/timeout
+	rm -f "$FW"
+	rmdir "$FWPATH"
+}
+
+load_fw()
+{
+	local name="$1"
+	local file="$2"
+
+	# This will block until our load (below) has finished.
+	echo -n "$name" >"$DIR"/trigger_request &
+
+	# Give kernel a chance to react.
+	local timeout=10
+	while [ ! -e "$DIR"/"$name"/loading ]; do
+		sleep 0.1
+		timeout=$(( $timeout - 1 ))
+		if [ "$timeout" -eq 0 ]; then
+			echo "$0: firmware interface never appeared" >&2
+			exit 1
+		fi
+	done
+
+	echo 1 >"$DIR"/"$name"/loading
+	cat "$file" >"$DIR"/"$name"/data
+	echo 0 >"$DIR"/"$name"/loading
+
+	# Wait for request to finish.
+	wait
+}
+
+trap "test_finish" EXIT
+
+# This is an unlikely real-world firmware content. :)
+echo "ABCD0123" >"$FW"
+NAME=$(basename "$FW")
+
+# Test failure when doing nothing (timeout works).
+echo 1 >/sys/class/firmware/timeout
+echo -n "$NAME" >"$DIR"/trigger_request
+if diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not expected to match" >&2
+	exit 1
+else
+	echo "$0: timeout works"
+fi
+
+# Put timeout high enough for us to do work but not so long that failures
+# slow down this test too much.
+echo 4 >/sys/class/firmware/timeout
+
+# Load this script instead of the desired firmware.
+load_fw "$NAME" "$0"
+if diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not expected to match" >&2
+	exit 1
+else
+	echo "$0: firmware comparison works"
+fi
+
+# Do a proper load, which should work correctly.
+load_fw "$NAME" "$FW"
+if ! diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not loaded" >&2
+	exit 1
+else
+	echo "$0: user helper firmware loading works"
+fi
+
+exit 0